A 7 year old girl presented with three episodes of massive hematemesis and melena. There is no history of jaundice. On examination, she had a large spleen, non-palpable liver and mild ascites. Poal vein was not visualized on ultrasonography. Liver function tests were normal and endoscopy revealed esophageal varices. The most likely diagnosis is:

A patent poal vein suggests diagnosis of Intrahepatic poal HTN unless the clinical picture indicates post sinusoid cause. In this patient poal vein is not visualised. Diagnosis of poal hypeension is established by demonstrating the presence of poosystemic collateral and/or raised poal pressure. Ref: Kliegman, Behrman, Jenson, Stanton (2008), Chapter 363, "Poal hypeension and varices", In the book, "NELSON TEXTBOOK OF PEDIATRICS", Volume 2, 18th Edition, New Delhi, Page 1709; O P Ghai Essential Pediatrics, 6th Edition, Page 294.